Acromioclavicular joint injuries.

OBJECTIVE: To discuss the anatomy and biomechanics of the acromioclavicular (AC) joint, along with the clinical evaluation and treatment of an athlete with an AC joint injury. DATA SOURCES: I searched MEDLINE from 1970 through 1999 under the key words "acromioclavicular joint," "clavicle," "acromioclavicular separation," and "acromioclavicular dislocation." Knowledge base was an additional source. DATA SYNTHESIS: AC joint injury is common in athletes and a source of significant morbidity, particularly for athletes in overhead sports. Because this injury can masquerade as other shoulder conditions, the examiner must understand the anatomy and biomechanics of the shoulder in order to perform a systematic clinical evaluation and identify the injury. CONCLUSIONS/RECOMMENDATIONS: Careful attention to the clinical evaluation allows the clinician to categorize the athlete's AC joint injury and institute appropriate treatment in a timely fashion, thus permitting the athlete to return to sport as quickly and safely as possible.